What is the maximum equivalent length of a boiler’s flue?
October 24th 2023
The maximum horizontal equivalent flue lengths (after the first elbow) is: 20m
The maximum vertical equivalent flue lengths is: 21m
Allow 1.3 meters of flue length for each 87° bend
1.0 meters of flue length for each 45° bend.
Maximum horizontal equivalent flue lengths (m) | Maximum vertical equivalent flue lengths (m) | 87° Elbow (m) | 45° Elbow (m) | |
NCB-CE | 20 | 21 | 1.3 | 1.0 |
NCB300 | 7 | 8 | 1.3 | 1.0 |
NCB500 | 7 | 8 | 1.3 | 1.0 |
NCB700 | 20 | 21 | 1.3 | 1.0 |
LCB700 | 20 | 21 | 1.3 | 1.0 |
NPE A/S | 20 | 21 | 2.4 | 1.2 |
Note: The maximum horizontal equivalent flue length is measured after the first elbow.
More news articles...

Nov 17th 2023
Advice
How to choose the right boiler
Choosing the right boiler is an important decision, but with all the options available, do you know which boiler is

Oct 25th 2023
Case Studies
A successful NCB700 ON installation in East Sussex
A customer of ours in East Sussex needed a boiler that was powerful enough to keep up with the day-to-day

Case Studies
Heating ON three floors
When a customer of ours found that a competing boiler was not up to the task of heating their large